The successful nationwide transport and evaluation of Multisystemic Therapy (MST) programs in Norway is described. This description is provided within the context of the nation's movement towards the adoption of evidence-based practices (EBPs) during the past decade, the conduct of a multisite randomized clinical trial to examine the effectiveness of MST in Norway, and the development of a center for effectively implementing and researching EBPs for child and adolescent problems. Data on Norwegian adolescent substance use, treatment, and research is summarized. Finally, challenges that have been addressed and overcome in achieving the large-scale adoption and implementation of MST are presented from the context of innovation diffusion. System-level barriers and strategies regarding funding, practice norms, local ownership, engaging stakeholders, geography, referral gatekeepers, and risk assessment are noted, as are practitioner level barriers and strategies regarding language, cultural appropriateness, caseload and compensation issues, and background and skill deficits. The Norwegian approach, in many ways, serves as an excellent model for importing and sustaining EBPs on a large-scale basis.